1. Field of the Invention
The invention relates to welding guns and refers more specifically to self-equalizing welding guns wherein equal pressure is applied on electrodes on opposite sides of a workpiece by means of a single welding gun, and refers more specifically to double-acting piston and cylinder structure in a self-equalizing welding gun positively actuated to sequentially move two electrodes into engagement with a workpiece on opposite sides thereof under substantially equal pressure and to subsequently increase the pressure equally on both electrodes to welding pressure with only a single actuating medium pressure and exhaust connection and without return springs, which structure and method is particularly simple, economical and efficient.
2. Description of the Prior Art
In the past, self-equalizing welding guns of the type wherein substantially equal pressure is applied to electrodes engaged with a workpiece on opposite sides thereof for welding purposes have been known. However, the prior self-equalizing welding guns often required spring return means to place the electrodes in their initial position after welding, or have required a plurality of pressure medium connections to exhaust piston and cylinder structure. Return springs and multiple pressure medium lines are often complicated, expensive and inefficient.